As for the Fosse Way, it only just touches the valley of the Thames. It crosses the line of the river in a high embankment a mile or so below its traditional source at Thames head, but above the point where the first water is seen. A small culvert running under that embankment takes the flood water in winter down the hollow, but no longer covers a regular stream.
Besides these four crossings of the old British ways above London Bridge there is the crossing of the Roman Road at Staines, which may or may not represent a passage older than the Roman occupation. We have no proof of its being older. The river is deep, and, unless the broken causeway on the Surrey shore is regarded as the remains of British work, there is no trace of a pre-Roman track in the neighbourhood.
The crossing at Staines was the main bridge over the middle river during the Roman occupation; no other spot on the banks (except London Bridge) is _certainly_ the site of a Roman bridge.
But apart from these there are two unsolved problems in connection with the roads across the Thames Valley in Roman times. The first concerns the passage of the upper Thames south of Eynsham; the second concerns the road which runs south from Bicester and Alchester.
As to the first of these, we know that the plain lying to the north of the Thames between the Cotswolds and the Chilterns was thoroughly occupied. We have also in the Saxon Chronicle a legendary account of the occupation of four Roman towns in this plain by the Saxon invaders. By what avenue did this wealthy and civilised district communicate with the wealthy and civilised south?
It is a question which will probably never be answered. There is no trace remaining of Roman bridges; perhaps nothing was built save of wood.
The obvious short-cut from the Roman town of Eynsham across the Witham peninsula to Abingdon bears no signs of a ford approached by Roman work or of a bridge, nor any record of such things.
As to the second question, the road from Bicester southward runs straight to Dorchester. At Dorchester, as we have seen, there was no ford, though just below it a Roman ferry has been guessed at.
There may have been a country road running down along the left or north bank of the river to the pre-historic crossing place at Goring and Streatley; but if there was, no trace of it remains, save perhaps in the two place names North Stoke and South Stoke.